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Some projects on ESP8266 boards
Particulates kill, build your sensor now!
One metric still missing from my home sensors is particulates, which are a known health hazard. Although I (secretly) already had a board running for a while, I wasn't satisfied enough to share it. Today, it's ready for sharing, including screaming headline for a change 
This board builds on my previous (smaller) design without particulate sensor, and also sports a custom-designed PCB (which you can order here!).
Starting with the end, it looks like:
:strip_exif()/f/image/p4to7QsT4oLYAqL9bHcUblWI.jpg?f=fotoalbum_medium "BigSensorThing mk1 final assembly front")
:strip_exif()/f/image/sAzk9VFyAVlUCMnYpccATE3s.jpg?f=fotoalbum_medium "BigSensorThing mk1 final assembly left")
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This board builds on my previous (smaller) design without particulate sensor, and also sports a custom-designed PCB (which you can order here!).
Starting with the end, it looks like:
:no_upscale():strip_icc():fill(white):strip_exif()/f/image/p4to7QsT4oLYAqL9bHcUblWI.jpg?f=user_large "BigSensorThing mk1 final assembly front")
:no_upscale():strip_icc():fill(white):strip_exif()/f/image/sAzk9VFyAVlUCMnYpccATE3s.jpg?f=user_large "BigSensorThing mk1 final assembly left")
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Measuring CO2/Temp/RH/Pressure with ESP8266 version 2
After experimenting a bit, I've made a new iteration of my ESP8266 sensor board, which now sports a PCB design (thanks all fellow Tweakers on GoT!). Some improvements::strip_exif()/f/image/UgT2q7JTIilkM3zhH8XmGAzG.jpg?f=fotoalbum_medium "https://tweakers.net/i/tV61FNC9QJHSHKrqv1p0z_NOLes=/234x176/filters:strip_icc():strip_exif()/f/image/UgT2q7JTIilkM3zhH8XmGAzG.jpg?f=fotoalbum_medium")
:strip_exif()/f/image/cgLZtKp17wLVWNjVW7H1Ge6r.jpg?f=fotoalbum_medium "https://tweakers.net/i/DcgcCbReammxIfe-Mq08WKVEOY0=/234x176/filters:strip_icc():strip_exif()/f/image/cgLZtKp17wLVWNjVW7H1Ge6r.jpg?f=fotoalbum_medium")
Update 20210207: made voltage regulator for BME280 requirement more explicit (thanks @ManS-H!)
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- More compact & uncluttered thanks to PCB
- Added one (optionally more distant) temperature sensor to prevent self-heating
- Added deep-sleep cycle to alternatively mitigate self-heating
:no_upscale():strip_icc():fill(white):strip_exif()/f/image/UgT2q7JTIilkM3zhH8XmGAzG.jpg?f=user_large "https://tweakers.net/i/tV61FNC9QJHSHKrqv1p0z_NOLes=/234x176/filters:strip_icc():strip_exif()/f/image/UgT2q7JTIilkM3zhH8XmGAzG.jpg?f=fotoalbum_medium")
:no_upscale():strip_icc():fill(white):strip_exif()/f/image/cgLZtKp17wLVWNjVW7H1Ge6r.jpg?f=user_large "https://tweakers.net/i/DcgcCbReammxIfe-Mq08WKVEOY0=/234x176/filters:strip_icc():strip_exif()/f/image/cgLZtKp17wLVWNjVW7H1Ge6r.jpg?f=fotoalbum_medium")
Update 20210207: made voltage regulator for BME280 requirement more explicit (thanks @ManS-H!)
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ESP8266 sensing CO2 + Temp + RH + Pressure
I've progressed somewhat in home-integrated sensors, and I've established a baseline for a connected home-environment sensor, which I document here.
Update: This design appears to cause some self-heating of the bme280 sensor, leading to a temperature of 2-3 degrees too high. Perhaps mounting it outside the 'case' solves this.
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Update: This design appears to cause some self-heating of the bme280 sensor, leading to a temperature of 2-3 degrees too high. Perhaps mounting it outside the 'case' solves this.
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Flash problems to ESP8266 boards
Note to self: sometimes I cannot write to ESP8266 boards. The solution appeared to be to disconnect serial devices first (e.g. MH-Z19B), then flash
Or use Arduino 'Serial logger'. Use baud 74880 for boot loader, 115200 for programs running on the board (in my case). This gave me:
Once I found the board was running Micropython (i.e. ruling out HW problem), I found that I could connect but not write to the Micropython prompt.
Symptoms
- Typically freshly bought boards (Wemos D1 mini Pro) running micropython
- esptool.py reports: A fatal error occurred: Failed to connect to Espressif device: Timed out waiting for packet header
- Arduino reports: error: espcomm_open failed error: espcomm_upload_mem failed
- Cannot interact or write to Micropython REPL prompt, commands are not fed back (i.e. I only have RX no TX capability)
Diagnosing ESP8266 boards
To see what the board is doing, connect to USB, then run screen on the tty:
screen /dev/tty.usbserial-1420 {74880,115200}
Or use Arduino 'Serial logger'. Use baud 74880 for boot loader, 115200 for programs running on the board (in my case). This gave me:
21:32:09.624 -> OSError: [Errno 2] ENOENT 21:32:09.624 -> 21:32:09.624 -> MicroPython v1.9.4-8-ga9a3caad0 on 2018-05-11; ESP module with ESP8266 21:32:09.624 -> Type "help()" for more information. 21:32:09.624 -> >>>
Once I found the board was running Micropython (i.e. ruling out HW problem), I found that I could connect but not write to the Micropython prompt.
Solution
In my case the problem appeared to be that a sensor using the serial port blocked my input to the serial port for uploading. Disconnecting the sensor worked. HTH.Measuring CO2 using MH-Z19B and D1 mini pro
In this article I describe how to measure CO2 levels using an MH-Z19B CO2 sensor connected to D1 mini pro and push these somewhere over wifi.
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